Dual Chamber Passive Retraction Needle Syringe

ABSTRACT

Embodiments of a retractable syringe assembly are provided that include a single syringe barrel configuration and dual syringe barrel configuration. In one or more embodiments, the assemblies include a barrel having a dividing wall to divide the chamber to define a fluid chamber having a first cross-sectional width for retaining fluid and a needle chamber for housing a needle hub assembly. The assemblies include a projection extending radially outwardly from the plunger rod to interact with a ramped portion of the dividing wall to cause the needle cannula to retract and be housed within the needle chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/222,923, filed on Mar. 24, 2014, which is a continuation of U.S.patent application Ser. No. 13/187,045, filed on Jul. 20, 2011, whichissued U.S. Pat. No. 8,721,599 on May 13, 2014, which claims priorityunder 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/366,749,filed Jul. 22, 2010, the disclosures of which are incorporated herein byreference in their entirety.

TECHNICAL FIELD

Aspects of the present invention relate to syringe assemblies thatinclude a retractable needle and reuse prevention features and methodsof using such syringe assemblies.

BACKGROUND

Needle retraction features have been incorporated into syringeassemblies to protect users from needle stick injuries. In conventionalassemblies, the needle hub assemblies including a needle cannula, areattached to the syringe barrel and must be withdrawn into the syringebarrel by a user or by a retraction feature. Alternatively, a needleshield may be placed over the needle cannula by the user or otherwise.

In conventional syringe assemblies in which the needle hub assembliesare retracted into the syringe barrel by a retraction feature, theretraction feature is often provided within the syringe barrel and/orthe plunger rod disposed within the syringe barrel. Specifically, theplunger rod may include a chamber that houses the needle hub after it isretracted. The retraction feature typically includes a cutting elementdisposed between the plunger rod and the stopper that is used to openthe stopper after the contents of the syringe barrel are expelled, toexpose the chamber of the plunger rod to receive the retracted needlehub. A spring is often incorporated in the needle hub assemblies todrive the retraction of the needle hub into the plunger rod.

Accordingly, such retraction features require cutting, braking, piercingor other force-intensive mechanical action for activation and, thus,increased complexity to enable the sealed plunger and stopper to bebreached during activation. Further, as most conventionally designedretractable needles are activated after dosing by continued pressure onthe rear of the plunger rod, inadvertent activation of the retractionfeature may occur since the same forces must be applied when expellingthe contents of the syringe barrel. Moreover, some devices may beinadvertently activated during dosing if sufficient pressure isgenerated during expulsion of the contents of the syringe, for example,when the medication is viscous and requires the user to apply additionalpressure or force to the plunger rod, which exceeds the force requiredto activate the retraction feature. Premature activation is especiallyproblematic in applications where high forces are applied to the plungerod, for example, during high speed injections.

The retraction features of conventional syringe barrels that areplunger-activated must withstand increased syringe pressures andassociated increase in force applied to the plunger rod, as describedabove. These increased forces and pressure leads to a requirement forlarge activation forces which could exceed the operational forces inorder to prevent premature activation. Since most conventional syringebarrels employ an additional plunger motion after full dispensing, andin the same manner as the dispensing motion, a threshold force must beused to allow the user to differentiate between a fully bottomed plungerand the activation of the retraction feature. The threshold force may bedifficult to ascertain and maintain separately from the force applied tothe plunger rod to expel the contents of the syringe barrel. Further,proper application of the threshold force may require a user to positionthe syringe barrel and the needle cannula at an increased angle to thepatient's skin, instead of positioning the syringe barrel and needlecannula substantially parallel to the patient's skin. The additionalforce required to activate the retraction feature may cause additionalpressure to be generated at the stopper or other removable opening inthe plunger rod, which may be sufficient to cause the stopper and/orplunger rod to malfunction.

In conventional syringe assemblies where the retraction feature and thesubsequent housing of the needle hub in conventional retractablesyringes are contained within the fluid path, the retraction feature andhousing may cause a volume of medication to become trapped within thesyringe barrel, thereby increasing waste and potentially affectingdosing accuracy. Further, a portion of the trapped medication may beexpelled during the activation of the retraction feature causingsplatter, if the retraction feature is activated when the needle cannulais outside of the patient, or an unintended increase in the doseadministered to the patient, if the retraction feature is activated whenthe needle cannula is in the patient. Placement of the retractionfeature within the syringe barrel may also cause trapped air to remainin the syringe barrel when purging or priming the syringe. This can leadthe possibility of injected air. The size of the syringe barrel mustalso accommodate the retraction feature and the needle hub assembly thatwill be housed therein after retraction.

In syringe assemblies which do not house the retraction feature withinthe fluid path, the retraction feature is often disposed at a locationthat requires the user to change their grip of the syringe assembly toactivate the retraction feature.

Conventional retraction syringe assemblies often do not incorporatereuse prevention features, and thus, the retraction mechanism may bereset so the syringe barrel may be reused. The reuse of syringeassemblies without sterilization or sufficient sterilization is believedto facilitate the transfer of contagious diseases. Further, theretraction features of conventional syringes also often require the userto actively activate the retraction mechanism. Accordingly, the chanceof human error in failure to activate or properly activate theretraction mechanism can lead to continued exposure of needles.

Accordingly, it would be desirable to provide a retractable syringeassembly with a retraction feature that does not interfere with normaloperation of the syringe assembly, is passively activated and reducesthe risk of premature activation or the retraction mechanism. It wouldalso be desirable to provide a retractable syringe assembly whichincorporates a reuse prevention feature.

SUMMARY OF THE INVENTION

One embodiment of the present invention pertains to a syringe assemblycomprising a fluid barrel including a sidewall having an inside surfacedefining a fluid chamber for retaining fluid and having a firstcross-sectional width, an open proximal end and a distal end including adistal wall; a plunger rod disposed within the fluid chamber comprisinga distal end, a proximal end, a plunger rod body extending from thedistal end to the proximal end, and a stopper disposed at the distal endof the plunger rod for forming a fluid-tight seal with the insidesurface of the barrel; a retraction barrel disposed adjacent to thesidewall of the fluid barrel, the retraction barrel including a wallhaving an interior surface defining a needle chamber, an open proximalend, an open distal end including a barrier wall, an aperture betweenthe wall of the fluid barrel and the sidewall of the fluid barrel suchthat the fluid chamber and the needle chamber are in fluid communicationand a needle hub assembly comprising a needle hub, a needle cannulaattached to the needle hub in fluid communication with the aperture, theneedle hub assembly biased to move in the proximal direction; and atrigger element moveable with the plunger rod and extending into theneedle chamber of the retraction barrel, the trigger element providing atrigger force causing the needle cannula to retract into the retractionbarrel.

In one or more embodiments of the present invention, the wall of asyringe assembly of the present invention includes a supporting elementthat engages a needle assembly disposed within the needle chamber andthe supporting element is positioned to apply a force in the distaldirection to the needle hub such that the needle cannula extendsdistally beyond the open distal end of the retraction barrel in firstposition.

In one or more embodiments of the present invention, the trigger elementprovides a trigger force on the needle hub to disengage the supportingelement and the needle hub so the needle cannula is housed within theretraction barrel.

In one or more embodiments of the present invention, the needle hub isbiased by a spring disposed between the needle hub and the barrier wallthat exerts a force on the needle hub in the proximal direction.

In one or more embodiments of the present invention, the trigger elementis attached to the distal end of the plunger rod. In one or moreembodiments of the present invention, the trigger element may include aproximal end attached to the proximal end of the plunger rod, a free andopen distal end that provides the trigger force, and a trigger elementbody extending from the proximal end to the distal end and including aninterior surface defining a hollow interior.

In one or more embodiments of the present invention, the inside surfaceof the syringe barrel includes a retaining ring adjacent said proximalend defining a second cross-sectional width that is less than the firstcross-sectional width and the plunger rod body includes a flexibleprotrusion having a cross-sectional width greater than thecross-sectional width of the barrel at the rib and a frangible portion.

In one or more embodiments of the present invention, the plunger rodbody comprises a distal portion and a proximal portion, the protrusiondisposed between the distal portion and the proximal portion. In one ormore embodiments of the present invention, the distal portion of theplunger rod body comprises a support member disposed proximally adjacentto the flexible protrusion and at least one frangible portion disposedproximally adjacent to the support member. In one or more embodiments ofthe present invention, the proximal end of the trigger element isattached to the thumbpress of the plunger rod. In one or moreembodiments of the present invention, the distal end of the plunger rodincludes a stopper-engaging portion and the stopper is attached to thestopper-engaging portion of the plunger rod, the stopper being distallyand proximally movable relative to the stopper-engaging portion for apre-selected axial distance such that when the distal end of the stopperis in contact with the distal wall of the barrel, the protrusion ispermitted to advance distally past the rib in the barrel and lock theplunger rod in the barrel to prevent reuse of the syringe assembly. Inone or more embodiments of the present invention, the stopper-engagingportion of the plunger rod is connected to the stopper such that uponapplication of an initial proximally directed force to the plunger rod,while holding the barrel, causes the plunger rod and the trigger elementto move the length of the axial distance in a proximal direction withinthe barrel, while the stopper remains stationary. In one or moreembodiments of the present invention, the stopper-engaging portion ofthe plunger rod is connected to the stopper such that upon applicationof a continuous proximally directed force to the plunger rod, whileholding the barrel, causes the stopper, the plunger rod and the triggerelement to move together in a proximal direction within the barrel. Inone or more embodiments of the present invention, the stopper-engagingportion of the plunger rod is connected to the stopper such thatapplication of an initial distally directed force to the plunger rodafter application of a proximally directed force to the plunger rod,while holding the barrel, causes the stopper to remain stationary andthe plunger rod and the trigger element to move the length of the axialdistance in the distal direction within the barrel. In one or moreembodiments of the present invention, the stopper-engaging portion ofthe plunger rod is connected to the stopper such that application of acontinuous distally directed force to the plunger rod causes thestopper, plunger rod and the trigger element to move together in thedistal direction within the barrel until the stopper reaches the distalend of the barrel. In one or more embodiments of the present invention,contact between the stopper and the distal wall of the barrel causes thesupport element to disengage from the needle hub and the protrusion toadvance distally past the rib in the barrel and lock the plunger rod inthe barrel to prevent reuse of the syringe assembly. In one or moreembodiments of the present invention, application of a proximallydirected force to the plunger, after the protrusion has advanceddistally past the rib, causes the at least one frangible portion of theplunger rod to break. In one or more embodiments of the presentinvention, application of a continuous proximally directed force on theplunger rod causes the stopper-engaging portion to disengage from thestopper.

In one aspect of the present invention, the open distal end of thetrigger element comprises a beveled edge that extends distally.

In one or more embodiments of the present invention, the retractionbarrel is disposed parallel to the fluid barrel.

Another embodiment of the present invention pertains to syringe assemblycomprising a barrel comprising including an open proximal end, sidewallhaving an inside surface defining a fluid chamber for retaining fluidand having a first cross-sectional width and a needle chamber forhousing a needle hub assembly, the fluid chamber and the needle chamberbeing divided by a barrier wall having a first aperture permitting fluidcommunication between the fluid chamber and the needle chamber, theneedle chamber including a flexible tab that extends into the needlechamber to engage a needle hub assembly disposed therein; a needle hubassembly disposed within the needle chamber, the needle hub assemblycomprising a needle hub, a needle cannula attached to the needle hub influid communication with the first aperture, the needle cannula biasedto move in the proximal direction, the flexible tab positioned to engagethe needle hub and apply a force in the distal direction to the needlehub so that the needle cannula extends beyond the open distal end of theretraction barrel in a positioned in first position; and a plunger roddisposed within the fluid chamber comprising a distal end, a proximalend, a stopper disposed at the distal end of the plunger rod for forminga fluid-tight seal with the inside surface of the barrel, a plunger rodbody extending from the distal end to the proximal end, and anactivation element disposed on the plunger rod to move the flexible taband cause the needle cannula to retract and be housed within theretraction barrel in a second position.

In one or more embodiments of the present invention, the needle cannulais biased to move in the proximal direction by a spring disposed betweenthe needle hub and the barrier wall that exerts a force on the needlehub and the spring is compressed when the flexible tab engages theneedle hub. In one or more embodiments of the present invention, theneedle chamber barrier wall further comprises a second aperture topermit the flexible tab to flex inwardly into the needle chamber and aramped portion that extends outwardly into the fluid chamber. In one ormore embodiments of the present invention, the disengagement of theflexible tab and the needle hub permits the spring to expand and causesthe needle hub to retract into the hollow interior of the triggerelement.

In one or more embodiments of the present invention, the trigger elementis disposed on the plunger rod body and extends radially outwardly fromthe plunger rod body. In one or more embodiments of the presentinvention, the barrel comprises a dose limit indicator disposed on anoutside surface of the sidewall. In one or more embodiments of thepresent invention, upon application of a force in the proximal directionon the plunger rod causes the plunger rod to move in the proximaldirection and aspirate a liquid into the fluid chamber and thesequential application of a force in the distal direction causes theplunger rod to engage the ramp and cause the flexible tab to flexoutwardly into the fluid chamber to release the force applied to theneedle hub in the distal direction. the inside surface of the side wallat the fluid chamber includes a retaining ring adjacent said proximalend defining a second cross-sectional width that is less than the firstcross-sectional width and the plunger rod body includes a flexibleprotrusion having a cross-sectional width greater than thecross-sectional width of the barrel at the rib and a frangible portion.

In one or more embodiments of the present invention, the contact betweenthe stopper and the distal wall of the barrel causes the flexible tab todisengage from the needle hub and the protrusion to advance distallypast the rib in the barrel and lock the plunger rod in the barrel toprevent reuse of the syringe assembly. In one or more embodiments of thepresent invention, the distal end of the plunger rod includes astopper-engaging portion and the stopper is attached to thestopper-engaging portion of the plunger rod, the stopper being distallyand proximally movable relative to the stopper-engaging portion for apre-selected axial distance such that when a force is applied to theplunger rod in the distal direction and the distal end of the stopper isin contact with the distal wall of the barrel, the protrusion ispermitted to advance distally past the rib in the barrel and lock theplunger rod in the barrel to prevent reuse of the syringe assembly.

Yet another embodiment of the present invention pertains to a syringeassembly comprising a fluid barrel including a sidewall having an insidesurface defining a fluid chamber for retaining fluid and having a firstcross-sectional width, an open proximal end and a distal end including adistal wall; a plunger rod disposed within the fluid chamber comprisinga distal end, a proximal end, a plunger rod body extending from thedistal end to the proximal end, and a stopper disposed at the distal endof the plunger rod for forming a fluid-tight seal with the insidesurface of the barrel; a retraction barrel disposed adjacent to thesidewall of the fluid barrel, the retraction barrel including a wallhaving an interior surface defining a needle chamber, an open proximalend, an open distal end including a barrier wall, an aperture betweenthe wall of the fluid barrel and the sidewall of the fluid barrel suchthat the fluid chamber and the needle chamber are in fluid communicationand a needle hub assembly comprising a needle hub, a needle cannulaattached to the needle hub in fluid communication with the aperture, theneedle hub assembly biased to move in the proximal direction; and aretraction mechanism to the needle cannula to retract into theretraction barrel, wherein the retraction barrel is nested with thefluid barrel and the retraction barrel has cross-sectional dimensionthat is less than 90% of the cross-sectional dimension of the fluidbarrel.

Yet another embodiment of the present invention pertains to a syringeassembly comprising a barrel comprising including an open proximal end,a distal end, a sidewall extending from the distal end and open proximalend defining a chamber having an inside surface, a dividing wall todivide the chamber to define a fluid chamber having a firstcross-sectional width for retaining fluid and a needle chamber forhousing a needle hub assembly, the dividing wall having a first aperturepermitting fluid communication between the fluid chamber and the needlechamber; a needle hub assembly disposed within the needle chamber, theneedle hub assembly comprising a needle hub, a needle cannula attachedto the needle hub in fluid communication with the first aperture, asecond conduit that extends from an open end of the needle cannula to asecond aperture of the needle chamber, the needle cannula biased to movein the proximal direction by a biasing element, the dividing wallincluding a supporting element that extends into the needle chamber toengage a needle hub and a ramped portion that extends into the fluidchamber, the supporting element applies a force in the distal directionto the needle hub so that the needle cannula extends beyond the opendistal end of the retraction barrel in a positioned in first position;and a plunger rod disposed within the fluid chamber comprising a distalend, a proximal end, a stopper disposed at the distal end of the plungerrod for forming a fluid-tight seal with the inside surface of thebarrel, a plunger rod body extending from the distal end to the proximalend, and a projection extending radially outwardly from the plunger rodto interact with the ramped portion of the dividing wall and cause theneedle cannula to retract and be housed within the needle chamber in asecond position.

In one or more embodiments of the present invention, the supportingelement in the first position provides a force on the needle hub in thedistal direction that is greater than a force applied to the needle hubin the proximal direction by the biasing element.

In one or more embodiments of the present invention, the supportingelement is a perpendicular tab that is disposed on the dividing wall.

In one or more embodiments of the present invention, the dividing wallincludes an opening to permit the perpendicular tab to flex outwardlyinto the fluid chamber as the plunger rod interacts with the rampedportion of the dividing wall.

In one or more embodiments of the present invention, a portion of thedividing wall adjacent to the perpendicular tab also flexes inwardly tomove the perpendicular tab.

In one or more embodiments of the present invention, the perpendiculartab holds the biasing element to maintain the needle hub assembly in thefirst position.

In one or more embodiments of the present invention, upon application ofa force in the proximal direction causes the perpendicular tab to movefrom the first position and allowing the biasing element to release theneedle hub assembly and move the needle hub assembly to the secondposition.

In one or more embodiments of the present invention, the second conduitincludes an opening to be aligned with the second aperture to permitfluid communication between the needle cannula and the fluid chamber.

In one or more embodiments of the present invention, the needle chamberhas cross-sectional dimension that is less than the firstcross-sectional dimension of the fluid chamber.

In one or more embodiments of the present invention, the inside surfaceof the fluid barrel includes a retaining ring adjacent said proximal enddefining a second cross-sectional width that is less than the firstcross-sectional width and the plunger rod body includes a flexibleprotrusion having a cross-sectional width greater than thecross-sectional width of the fluid barrel at the retaining ring.

In one or more embodiments of the present invention, the plunger rodbody comprises a distal portion and a proximal portion, the protrusiondisposed between the distal portion and the proximal portion.

In one or more embodiments of the present invention, the distal portionof the plunger rod body comprises a support member disposed proximallyadjacent to the flexible protrusion and at least one frangible portiondisposed proximally adjacent to the support member.

In one or more embodiments of the present invention, the distal end ofthe plunger rod includes a stopper-engaging portion and the stopper isattached to the stopper-engaging portion of the plunger rod, the stopperbeing distally and proximally movable relative to the stopper-engagingportion for a pre-selected axial distance such that when the distal endof the stopper is in contact with the distal wall of the barrel, theprotrusion is permitted to advance distally past the rib in the barreland lock the plunger rod in the barrel to prevent reuse of the syringeassembly.

In one or more embodiments of the present invention, contact between thestopper and the distal wall of the barrel causes the support element todisengage from the needle hub and the protrusion to advance distallypast the rib in the barrel and lock the plunger rod in the barrel toprevent reuse of the syringe assembly.

In one or more embodiments of the present invention, application of aproximally directed force to the plunger, after the protrusion hasadvanced distally past the rib, causes the at least one frangibleportion of the plunger rod to break.

In one or more embodiments of the present invention, application of acontinuous proximally directed force on the plunger rod causes thestopper-engaging portion to disengage from the stopper.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a retractable syringe assemblyaccording to one or more embodiments;

FIG. 2 illustrates an exploded view of the syringe assembly according toone or more embodiments;

FIG. 3 illustrates a cross-sectional view of the syringe assembly ofclaim 2;

FIG. 4 illustrates a cross-sectional side-view of the fluid barrel andthe retraction barrel shown in FIG. 1;

FIG. 5 illustrates a cross-sectional side-view of the plunger rod andstopper shown in FIG. 1;

FIG. 6 illustrates a cross-sectional side-view of the needle hubassembly in FIG. 1;

FIG. 6A illustrates a partial exploded view of the syringe assemblyshown in FIG. 6;

FIG. 7 illustrates a cross-sectional view of the syringe assembly ofFIG. 1 after a force in the proximal direction has been applied to theplunger rod to fill the fluid chamber with liquid;

FIG. 7A illustrates a partial exploded view of the syringe assemblyshown in FIG. 7;

FIG. 8 illustrates a cross-sectional view of the syringe assembly ofFIG. 7 after a force in the distal direction has been applied to theplunger rod to expel the liquid from the fluid chamber;

FIG. 8A illustrates a partial exploded view of the syringe assemblyshown in FIG. 8;

FIG. 9 illustrates a cross-sectional view of the syringe assembly ofFIG. 8 after all of the liquid has been expelled from the fluid chamberand the stopper is in contact with the distal wall;

FIGS. 9A and 9B illustrate partial exploded views of the syringeassembly shown in FIG. 9;

FIG. 10 illustrates a cross-sectional view of the syringe assembly ofclaim 9 after the needle hub assembly is retracted into the retractionbarrel

FIG. 11 illustrates a cross-sectional view of the syringe assembly ofFIG. 10 after a force is applied on the plunger rod in the proximaldirection, after the plunger rod is locked within the fluid barrel;

FIG. 11A illustrates a partial exploded view of the syringe assemblyshown in FIG. 11;

FIG. 12 illustrates a perspective view of a retractable syringe assemblyaccording to one or more embodiments;

FIG. 13 illustrates an exploded view of the syringe assembly of claim12;

FIG. 14 illustrates a cross-sectional view of the syringe assembly ofclaim 13;

FIG. 15 illustrates a cross-sectional side-view of the fluid barrel andthe retraction barrel shown in FIG. 12;

FIG. 16 illustrates a cross-sectional side-view of the plunger rod shownin FIG. 12;

FIG. 17 illustrates a cross-sectional side-view of the needle hubassembly in FIG. 12;

FIG. 18 illustrates a cross-sectional view of the syringe assembly ofFIG. 12 after a force in the proximal direction has been applied to theplunger rod to fill the fluid chamber with liquid;

FIG. 19 illustrates a cross-sectional view of the syringe assembly ofFIG. 18 after a force in the distal direction has been applied to theplunger rod to expel the liquid from the fluid chamber;

FIG. 20 illustrates a cross-sectional view of the syringe assembly ofFIG. 19 after all of the liquid has been expelled from the fluid chamberand the stopper is in contact with the distal wall;

FIG. 21 illustrates a cross-sectional view of the syringe assembly ofclaim 20 after the needle hub assembly is retracted into the retractionbarrel

FIG. 22 illustrates a cross-sectional view of the syringe assembly ofFIG. 21 after a force is applied on the plunger rod in the proximaldirection, after the plunger rod is locked within the fluid barrel;

FIG. 23 illustrates a cross-sectional side view of a retractable syringeassembly according to one or more embodiments, with fluid filled in thefluid chamber;

FIG. 23A illustrates a partial exploded view of the syringe assemblyshown in FIG. 23;

FIG. 24 illustrates a cross-sectional side view of the retractablesyringe assembly shown in FIG. 23 after a force is applied to theplunger rod in the distal direction;

FIG. 25 illustrates a cross-sectional side view of a retractable syringeassembly shown in FIG. 24 after the fluid is expelled from the fluidchamber;

FIG. 25A illustrates a partial exploded view of the syringe assemblyshown in FIG. 25;

FIG. 26 illustrate cross-sectional view of the syringe assembly of claim25 after the needle hub assembly is retracted into the retractionbarrel; and

FIG. 27 illustrates a cross-sectional view of the syringe assembly ofFIG. 26 after a force is applied on the plunger rod in the proximaldirection, after the plunger rod is locked within the fluid barrel.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the invention, it isto be understood that the invention is not limited to the details ofconstruction or process steps set forth in the following description.The invention is capable of other embodiments and of being practiced orbeing carried out in various ways.

In this disclosure, a convention is followed wherein the distal end ofthe device is the end closest to a patient and the proximal end of thedevice is the end away from the patient and closest to a practitioner.

A first aspect of the present invention pertains to a retractablesyringe assembly having a passive retraction feature. The retractablesyringe assembly 100 of one or more embodiments utilizes a dual syringebarrel or a syringe barrel that isolates the fluid chamber from theretraction feature.

In the embodiment shown in FIGS. 1-11, the retractable syringe assemblyincludes a dual syringe barrel 101 that includes fluid barrel 110 and aretraction barrel 120. The retractable syringe also includes a needlehub assembly 140, a plunger rod 160, stopper 170 and a trigger element190. The fluid barrel shown in FIG. 4, includes a distal end 111, a openproximal end 119, a sidewall 112 extending from the distal end 111 andthe proximal end 119 including an inside surface 114 defining a chamber115. The inside surface 114 defines a cross-sectional width and mayinclude a reuse prevention feature, that will be discussed in greaterdetail below. The distal end 111 includes a distal wall 117 thatencloses the distal end 111. In the embodiment shown, the sidewall 112includes a first aperture 118 for permitting fluid communication betweenthe fluid barrel and the retraction barrel. As will be discussed ingreater detail below, the first aperture 118 also permits fluidcommunication between a needle cannula disposed within the retractionbarrel 120 and the fluid barrel 110.

The fluid barrel 110 shown in FIG. 4, include a reuse preventionfeature. Specifically, the fluid barrel 110 includes a retaining element116 shown in the form of a rib that extends around the entirecircumference of the inside surface 114 of the fluid barrel 110 at alocation adjacent to the proximal end 119 of the fluid barrel. Thecross-sectional width of the inside surface 114 at the retaining element116 is less than the first cross-sectional width or the cross-sectionalwidth of the inside surface 114 at the remaining locations along thelength of the fluid barrel. In one or more embodiments, optional tabs ordetents can be used to create a region of the fluid barrel 110 having across-sectional width that is less than the first cross-sectional widthof the fluid barrel 110. The retaining ring 116 may also be shaped tofacilitate activation of the reuse prevention feature. For example, thefluid barrel 110 may also include a diameter transition region disposedproximally adjacent to the retaining element 116 at the proximal end 119of the fluid barrel 110. The cross-sectional width of the inside surface114 of the fluid barrel at the diameter transition region increases fromthe distal end 111 to the proximal end 119 of the fluid barrel 110. Aswill be described in greater detail below, in embodiments of theretractable syringe assembly that utilize a reuse prevention feature,the reuse prevention feature of the fluid barrel 110 cooperates withcorresponding reuse prevention features on the plunger rod 160 to lockthe plunger rod 160 within the fluid barrel 110 and/or to disable theplunger rod 160 from further use.

In an alternative embodiment, the retractable syringe assembly mayinclude a single barrel, wherein a portion of the barrel is divided by adividing wall into a fluid barrel and the remaining portion of thebarrel that houses the retraction feature and the needle hub assembly.The dividing wall may include an aperture for permitting fluidcommunication between the fluid barrel and the remaining portion of thebarrel that houses the retraction feature and the needle hub assembly.

The retraction barrel 120 is disposed adjacent to the sidewall 112 ofthe fluid barrel 110 in the embodiment shown in FIG. 4. The retractionbarrel 120 is configured to house a needle hub assembly 140 therein andthe retraction feature. The retraction barrel 120 includes an opendistal end 121 and an open proximal end 129. A wall 122 having aninterior surface 124 defining the needle chamber 125 extends from theopen distal end 121 to the open proximal end 129. The wall 122 of theretraction chamber is adjacent to the sidewall 112 of the fluid barrel110. In one or more embodiments, the wall 122 may extend around theportions of the retraction barrel 120 that are not in direct contactwith fluid barrel 110 and the sidewall 112 may form the barrier betweenthe retraction barrel 120 and the fluid barrel 110. In other words, theoutside surface of the sidewall 112 may form the interior surface 124 ofthe retraction barrel 120 along the portion of the retraction barrel 120that is in direct contact with the fluid barrel 110.

The size of the needle chamber 125 may be modified to accommodate theneedle hub assembly 140 and/or the retraction feature. According to oneor more embodiments, the interior surface 124 of the retraction barrel120 has a cross-sectional width that is smaller than the firstcross-sectional width of the fluid barrel 110. In specific embodiments,the cross-sectional width of the interior surface 124 of the retractionbarrel is less than about 90%, 80%, 70%, 60%, 50%, 40%, 30%, or 20% ofthe cross-sectional width of the inside surface 114 of the fluid barrel.Such designs in which the cross-sectional width of the interior surface124 of the retraction barrel is less than the cross-sectional width ofthe inside surface 114 of the fluid barrel, provides ergonomic andfunctional advantages. For example, the overall appearance and handlingof the dual barrel syringe is more appealing to the user. In certainembodiments, the retraction barrel can be nested within the fluidbarrel. For example, both the retraction barrel and the fluid barrel mayboth be bounded or circumscribed by a common wall, and the retractionbarrel may be partially or fully disposed within the fluid barrel, oralternatively, a dividing wall may separate a single barrel into twoseparate barrels, a fluid barrel and a retraction barrel.

The open distal end 121 of the retraction barrel 120 in the embodimentshown includes a barrier wall 127 that partially encloses the opendistal end 121. The open distal end 121 may be free of a barrier wall127 and may be fully open. The wall 122 may include a second aperture128 that permits fluid communication with the fluid chamber 115 and theneedle chamber 125. The second aperture 128 of the wall may also allowfluid communication between the fluid chamber 115, needle chamber 125and the needle cannula. The fluid communication between the fluid barrel110 and retraction barrel 120 may be provided by a first conduit 130that extends from a first aperture 118 of the fluid barrel 110 and thesecond aperture 128 of the retraction barrel. In the embodiment shown,the first conduit 130 extends along the width of the sidewall 112 andthe wall 122.

The needle hub assembly may include a second conduit 132 that extendsfrom an open end of the needle cannula to second aperture 128 of theretraction barrel. The second conduit 130 may include an opening 133that must be aligned with the second aperture 128 to permit fluidcommunication between the needle cannula and the fluid barrel.

The needle hub assembly 140 is disposed within the retraction barrel 120and includes a needle hub 142 and a needle cannula 150 attached to theneedle hub 142. The needle hub 142 includes a distal end 141 and aproximal end 149. The needle cannula 150 includes a free and open distalend 151 and an open proximal end 159 that is attached to the distal end141 of the needle hub. The needle hub 142 shown in FIGS. 6 and 6Ainclude a needle hub body 144, a needle hub support 146 disposeddistally adjacent to the needle hub body and a needle hub extension 148that extends in the proximal direction from the needle hub body 144. Asshown in FIG. 6A, the needle hub support 146 includes a recessed portion147 for partially housing the proximal end 159 of the needle cannula. Inthe embodiment shown, the recessed portion 147 includes a portion of thesecond conduit 132 that extends through the needle hub 142 to the secondaperture 128 of the retraction barrel. In one or more alternativeembodiments, the proximal end 159 of the needle cannula may extendthrough the recessed portion 147 to the second conduit 132, which islocated fully within the needle hub body 144 and does not extend intothe needle cannula support 146. The needle hub extension 148 extendsinto the needle chamber 125 and forms part of the retraction feature ofthe retractable syringe assembly 100. The needle hub extension 148, asshown in FIG. 6, is provided in the form of an elongate rod that iscylindrical in shape. However, the needle hub extension may have othershapes. The needle hub extension 148 includes a latch portion 145 thatextends radially outwardly from the needle hub extension 148.

The needle cannula 150 of the needle hub assembly 140 is biased to movein the proximal direction. In the embodiment shown, the needle hubassembly 140 is biased to move in the proximal direction, therebybiasing the attached needle cannula 150. In the embodiment shown, theneedle hub assembly 140 is biased to move in the proximal direction by abiasing element 152 disposed between the needle hub 142 and the barrierwall 127 of the retraction barrel 120. The biasing element 152 mayinclude a spring 153, which may be a compression spring that applies aconstant force on the needle hub 142 in the proximal direction. Inalternative embodiments, the biasing element 152 may be provided inanother form, for example, a lever arm (not shown) may be disposedbetween the needle hub and the barrier wall. The retraction barrel 120includes a supporting element 134 that prevents the needle hub frommoving in the proximal direction. As will be explained in greater detailbelow, the release of the supporting element 134 will allow the biasedneedle hub 142 and the needle cannula 150 attached thereto to retractinto the retraction barrel 120. In one or more variants, a portion ofthe needle hub 142 may be biased. For example, the needle cannulasupport 146 and the needle hub extension 148 may be provided as separatecomponents from the needle hub body 144 and may be biased such that whenthe support element 134 is released, the needle hub extension 148 andthe needle cannula support 146 may be retracted with the needle cannula150 into the retraction barrel 120, while the needle hub body 144remains stationary.

The needle hub assembly is sized moveable within the needle chamber. Thesize and shape of the needle hub assembly may be modified to permitmovement in needle chambers having different sizes. In the assembledstate, prior to use, the needle hub assembly is positioned at the opendistal end of the retraction barrel.

The wall 122 of the retraction barrel 120 includes the supportingelement 134 that engages at least a portion of the needle hub assembly140 or interacts with the needle hub assembly 140 to provide a force inthe distal direction to the needle hub assembly 140 such that the needlehub assembly 140 is positioned at the open distal end 121 of theretraction barrel. Specifically, the needle hub assembly 140 ispositioned so the needle cannula 150 extends beyond the open distal end121 of the retraction barrel in a first position. In the first position,the supporting element 134 provides a force on the needle hub 142 in thedistal direction that is greater than the force applied to the needlehub 142 in the proximal direction by the biasing element 152. Thesupporting element 134 in the embodiment shown is provided in the formof a flexible arm 135 that is attached to the wall 122 of the retractionbarrel. The wall 122 includes an opening 136 that permits the flexiblearm 135 to flex outwardly. In the embodiment shown, the flexible arm 135includes a distal end 137 that is attached to the wall 122 and a freeproximal end 138 including a tab 139 that extends radially inwardly intothe needle chamber 125. The tab 139 supports the proximal end 149 of theneedle hub by engaging the latch portion 145. The tab 139 and theflexible arm 135 are sized and shaped to engage the latch portion 145and support the needle hub 142 and the needle cannula 150. The tab 139and the flexible arm 135 are also sized and shaped to compress thebiasing element 152 so the needle hub assembly is positioned in thefirst position. To retract the needle cannula 150 into the retractionbarrel 120, as will be described in greater detail below, the flexiblearm 135 is moved to release the latch portion 145. In other words, theflexible arm 135 is moved to a position in which the tab 139 can nolonger support the needle hub extension 148 and apply a force on theneedle hub extension 148 or needle hub 142 in the distal direction thatis greater than force applied to the needle hub 142 in the proximaldirection by the biasing element 152.

In an alternative embodiment, the supporting element 134 may be providedin the form of a frangible section that extends inwardly from the wall122 of the retraction barrel. The frangible section may include abreakable shelf that supports the needle hub assembly 140. The frangiblesection may break to release needle hub assembly or to no longer apply aforce on the needle hub extension 148 or needle hub 142 in the distaldirection that is greater than force applied to the needle hub 142 inthe proximal direction by the biasing element 152.

A plunger rod 160 is disposed within the fluid chamber 125 and shownmore clearly in FIG. 5. The plunger rod 160 includes a distal end 161and a proximal end 169. The plunger rod 160 includes a stopper-engagingportion 162 extending from the distal end 161 to a plunger rod body 163.In one or more embodiments, the plunger rod body 163 may extend from thestopper-engaging portion 162 to the proximal end 169 of the plunger rod.In the embodiment shown in FIG. 5, the plunger rod body 163 extends fromthe stopper-engaging portion 162 to a reuse prevention feature thatextends from the plunger rod body 163 to a thumb press 164 that isdisposed at the proximal end 169 of the plunger rod. The thumb press 164may include a thumb press support 184.

The stopper-engaging portion 162 includes an annular disc 165 disposedat the distal end of the plunger rod and a narrowed portion 166extending from the annular disc 165 to the plunger rod body 163. Theannular disc 165 engages a stopper 170 so it is disposed at the distalend of the plunge rod. In one or more embodiments, the narrowed portion166 of the plunger rod 160 and the stopper 170 may be shaped to providerelative movement of the plunger rod 160 with respect to the stopper170. In one or more alternative embodiments, the plunger rod 160 may beattached to the stopper 170 in a fixed relationship.

As shown in FIG. 5, the stopper 170 has a distal end 171, a proximal end179, a stopper body 172 and a peripheral edge 173 which forms a sealwith the inside surface 114 of the fluid barrel 110. In one or moreembodiments, the peripheral edge 173 of the stopper 170 hascross-sectional width that permits the stopper 170 to slide in theproximal and distal directions within the fluid barrel. The stopper 170may include an optional elongate tip (not shown) on its distal end 171to facilitate reduction of the residual fluid and expulsion of fluidfrom the fluid barrel.

The stopper 170 includes a stopper body 174 extending from theperipheral edge 173 to the proximal end 179. The stopper body 174includes a recess 175 that is defined by an inside surface 176. Therecess 175 includes a neck portion 177 disposed adjacent to the proximalend 179, wherein the cross-sectional width of the inside surface 176 atthe neck portion 177 is less than the cross-sectional width of theinside surface 176 at the remaining locations of the recess 175. Therecess 175 allows the stopper-engaging portion 162 of the plunger rod160 to connect to the stopper 170. The annular disc 165 engages the neckportion 177 to retain the stopper 170 on the plunger rod 160. In one ormore alternative embodiments, detents (not shown) or tabs (not shown) onthe stopper 170 and/or the stopper-engaging portion 162 may be used toretain the stopper 170 on the plunger rod 160.

In one or more embodiments, the cross-sectional width of the insidesurface 176 may be sized and/or shaped to prevent relative movement ofthe stopper-engaging portion 162 within the recess 175. In theembodiment shown in FIG. 5, the cross-sectional width of the insidesurface 176 of the stopper is sized and shaped to permit relativemovement of the stopper-engaging portion 162 within the recess 175.Alternatively, the annular disc 165 and/or the narrowed portion 166 maybe shaped and/or sized to permit or prevent relative movement of thestopper-engaging portion 162 within the recess 175.

The stopper is typically made of plastic or other easily disposableand/or recyclable material. It may be desirable to incorporate naturalor synthetic rubber in the stopper or use a natural or synthetic rubberseal with the stopper. It will be understood that the stopper mayincorporate multiple seals.

The retractable syringe assembly 100 also includes a trigger element 190that includes a distal end 191 and a proximal end 199. The triggerelement 190 is moveable with the plunger rod 160 but extends into theneedle chamber 125 of the retraction barrel 120. In the embodimentshown, the trigger element 190 is attached to the thumb press support184 of the plunger rod. In one or more variants, the trigger element 190may be provided separately but configured to move with the plunger rod160 in the distal direction when a distally directed force is applied tothe plunger rod 160. In such embodiments, the trigger element 190 andthe plunger rod 160 move together in the distal direction when a userapplies a force on the plunger rod 160 in the distal direction.

The trigger element 190 is sized, shaped and positioned to provide atrigger force on the needle hub 142 to disengage the supporting element134 and the latch portion 145 so the needle cannula 150 retracts and ishoused into the retraction barrel. The trigger element 190 includes atrigger element body 192 that extends from the distal end 191 to theproximal end 199. The trigger element body 192 is shaped to have acylindrical shape and is elongate. In the embodiment shown, the triggerelement 190 has an open distal end 191 and the trigger element body 192has a hollow interior 193 to house the needle hub 142 and the needlecannula 150. The proximal end 199 of the trigger element is closed andmay be tapered to retain the needle hub 142 within the hollow interior193 after the needle hub 142 and the needle cannula 150 is retractedinto retraction barrel.

The open distal end 191 of the trigger element may have a beveled edgethat flexes or moves the flexible arm 135 radially outwardly. Themovement of the flexible arm 135 radially outwardly causes the tab 139to also move radially outwardly so it is no longer engaging the latchportion 145 or supporting the needle hub extension 148. The movement ofthe tab 139 releases the force applied to the needle hub extension 148in the distal direction by the tab 139 and, as a result, the forceapplied on the needle hub 142 by the biasing element 152 in the proximaldirection, which remains due to the compression of the biasing element152, causes the needle hub 142 to retract or move into the retractionbarrel 120 or specifically, the hollow interior 193 of the triggerelement.

Embodiments described herein utilize a passive retraction mechanismbecause the trigger element 190 is activated when the user applies aforce on the plunger rod in the distal direction to expel the contentsof the fluid barrel 110. Specifically, the trigger element 190 and theretraction feature are only activated when the full dose of medicationor the entire contents of the fluid barrel 110 are expelled.Accordingly, the retraction syringe assemblies described herein areinsensitive to hydraulic pressure generated during high speed injectionsor injections of viscous liquids from the fluid barrel, which oftencause premature activation. Further, the independent retraction barreland the housing of the retraction feature therein allows the retractionsyringe barrel to have a low activation force that is based solely onthe movement of the trigger element 190 in the distal direction or theapplication of the trigger force on the support element 134 to disengagefrom the needle hub 142. Accordingly, in the embodiments describedherein, retraction of the needle hub 142 and needle cannula 150 does notrequire cutting, braking, piercing or other force-intensive mechanicalaction, but rather relies on the flexing of the support element 134 andthe tab 139 to release the force applied to the needle hub 142 in thedistal direction that counteracts the force applied to the needle hub inthe proximal direction.

In the embodiment shown, the plunger rod 160 includes a reuse preventionfeature. Specifically, the plunger rod 160 includes a flexibleprotrusion 167 disposed proximally adjacent to the plunger rod body 163and a frangible portion 168 disposed between the flexible protrusion 167and the thumb press 164. The plunger rod 160 may be characterized suchthat the plunger rod body 163 extends from the stopper-engaging portion162 and includes a distal portion and a proximal portion wherein theflexible protrusion 167 is disposed between the distal portion and theproximal portion. The proximal portion includes the frangible portion168.

The protrusion 167 has a cross-sectional width that is greater than thecross-sectional width of the inside surface 114 of the fluid barrel 110at the retaining element 116. In at least one embodiment, theretractable syringe assembly is configured to allow the protrusion 167to advance distally past the retaining element 116, to lock the plungerrod 160 in the fluid barrel 110 when the user bottoms out the plungerrod 160 in the barrel or when the stopper 170 is in contact with thedistal wall 117 of the fluid barrel when all the contents of the fluidbarrel 110 have been expelled. Specifically, when the plunger rod 160 ismoved in the distal direction within the fluid barrel 110 uponapplication of a distally directed force on the plunger rod, theprotrusion 167 moves distally past the retaining element 116. In theembodiment shown, movement of the protrusion 167 distally past theretaining element 116 occurs as the stopper 170 is in contact with thedistal wall 117 of the fluid barrel. The smaller cross-sectional widthof the inside surface 114 of the fluid barrel at the retaining element116 prevents movement of the plunger rod 160 in the proximal directiononce the protrusion 167 has moved distally past the retaining element116. In one or more variants, the protrusion 167 may include aperipheral edge having a tapered portion (not shown) that facilitatesdistal movement of the protrusion 167 distally past the retainingelement 116 and into the fluid barrel 110, as will become apparent inthe subsequent discussion of operation of the syringe. The flexibleprotrusion 167 may also flex in the proximal direction as it movesdistally past the retaining element 116.

In the embodiment shown, the plunger rod 160 further includes afrangible portion 168 for separating at least a portion of the plungerrod from the remaining portion of the plunger rod 160 when a userapplies sufficient proximal force to the plunger rod 160 after it hasbeen locked within the fluid barrel 110. In the embodiment shown, thefrangible point 168 is located between the protrusion 167 and the thumbpress 164. It will be understood that the frangible portion 168 shown isexemplary, and other suitable means for permanently damaging the plungerrod or otherwise separating at least a portion of the plunger rod fromthe main body may be provided. In the embodiment shown, the frangibleportion 168 includes a support member 180 that extends from the flexibleprotrusion 167 to a plurality of point connections 181 that connect thesupport member 180 to the thumb press 164. The support member 180 shownin FIG. 5 has a distal end 182 and a proximal end 183. Thecross-sectional width of the support member 180 increases from thedistal end 182, adjacent to the flexible protrusion 167, to the proximalend 183, where the plurality of point connections 181 is disposed. Thesupport member 180 is shown as having a circular cross-section and theplurality of point connections 181 is disposed at the peripheral edge ofthe proximal end 183 of the support member 180. The point connections181 are discrete connections that form a narrowed connection pointbetween the support member 180 and the thumb press 164. It will beunderstood that a single point connection 181 may also be utilized toform a narrowed connection point between the support member 180 and thethumb press 164. The thumb press support 184 may further support thethumb press and connect the plurality of point connections 181 to thethumb press 164.

In use, when the flexible protrusion 167 has advanced distally past theretaining element 116, and the user applies a force in the proximaldirection on the plunger rod, the force required for the flexibleprotrusion 167 to overcome the retaining element 116 exceeds the forcerequired to break the plurality of point connections 181.

In embodiments which utilize a stopper and plunger rod that permitrelative movement of the plunger rod with respect to the stopper, thisrelative movement permits the stopper to be in contact with the distalwall 117 prior to use so that air within the fluid barrel is minimized,while still allowing the flexible protrusion to remain proximallyadjacent to the retaining element and thus, allowing movement of theplunger rod in the distal and proximal directions. In this position, theannular disc 165 is disposed adjacent to the neck portion 177 of thestopper and the length of the plunger rod and stopper is maximized. Inother words, in such embodiments, when the stopper 170 is attached tothe stopper-engaging portion 162, and the annular disc 165 engages theneck portion 177, there is a gap between the stopper 170 and the plungerrod body 163 defining a pre-selected axial distance 102. In thisposition, the user may apply a force on the plunger rod in the proximaldirection to draw fluid or liquid into the fluid chamber and the stopperand the plunger rod will remain in the same position with their combinedlength maximized. Specifically, when the user applies a force to theplunger rod 160 in the proximal direction, the plunger rod 160 and thestopper 170 move together in the proximal direction, while thestopper-engaging portion 162 is connected to the stopper 170 by the neckportion 177. In this configuration, the gap defining the pre-selectedaxial distance 102 is maintained while the stopper 170 and plunger rod160 move together in the proximal direction.

As shown in FIG. 7, the user applies proximal force to the plunger roduntil a predetermined or desired amount of liquid is aspirated or drawninto the syringe. During the aspiration step, the plunger rod and thestopper body move in the proximal direction together to draw medicationinto the syringe, while maintaining the pre-selected axial distance 102.As shown in FIGS. 7 and 7A, the trigger element 190 does not provide thetrigger force and the support element 134 and the tab 139 continue toengage the latch portion 145 and support the needle hub extension 148.

When a distal force is applied to the plunger rod 160 during aninjection or expulsion step to expel the contents of the fluid barrel110 the distally-directed force closes the gap and causes the plungerrod 160 to move the pre-selected axial distance 102, while the stopper170 remains stationary, as shown in FIG. 8. Consistent with at least oneembodiment, once the stopper-engaging portion 162 has distally moved thepre-selected axial distance 102 within the recess 175, it is no longerin contact with the neck portion 177. After this relative movement ofthe plunger rod 160 with respect to the stopper 170, the stopper 170 andthe plunger rod 160 begin to move in tandem in the distal direction. Inthis position, the length of the plunger rod and the stopper isshortened.

In one embodiment, as shown in FIGS. 8 and 8A, the user may inject alimited amount of the fluid aspirated or exert a limited force on theplunger rod 160 in the distal direction to flush or expel some of theaspirated fluid, without locking the plunger rod 160 within the fluidbarrel 110, provided that the flexible protrusion 167 remains positionedproximally adjacent to the retaining element 116. However, as will bedescribed further below, a user will typically expel substantially allof the contents of the fluid barrel by bottoming the stopper 170 againstthe distal wall 117 of the fluid barrel. As the user applies a force inthe distal direction to the plunger rod 160, the trigger element 190moves within the retraction barrel 120 with the plunger rod 160, as itmoves within the fluid barrel 110 in the distal direction.

As described above and shown in FIGS. 9-9B when the stopper is incontact with the distal wall 117, the flexible protrusion 167 will havemoved distally past the retaining element 116, due to the shortenedlength of the plunger rod 160 and the stopper 170 caused by the relativemovement of the plunger rod 160 with respect to the stopper 170. Thetrigger element 190 applies a trigger force to the support element 134causing the support element 134 to flex radially outwardly or to moveradially outward. When the support element 134 moves radially outwardly,the tab 139 no longer applies a force to the needle hub extension 148 inthe distal direction and the force applied by the biasing element 152 inthe proximal direction causes the needle hub 142 and the needle cannula150 to move into the retraction barrel 120, as shown in FIG. 10.

Referring now to FIGS. 11 and 11A, which illustrate the syringe assemblyafter the plunger rod 160 has been locked inside the fluid barrel 110,as a user attempts to reuse the retractable syringe assembly by applyinga force to the plunger rod 160 in the proximal direction, theapplication of a proximally-directed force to the plunger rod that isgreater than the force required to break the plurality of pointconnections 181 causes a portion of the plunger rod 160 to separate atthe plurality of point connections 181. The plurality of pointconnections 181 breaks because the force exerted by the retainingelement 116 on the flexible protrusion 167 exceeds the breaking force ofthe plurality of point connections 181.

As the portion of the plunger rod 160 is removed from the remainingportion of the plunger rod, as shown in FIG. 11, the needle hub assembly140 remains within the retraction barrel 120. The needle cannula 150 ishoused completely within the retraction barrel 120. As shown in FIG.11A, the support element 134 and the tab 139 are no longer flexedbecause the trigger element 190 no longer applies the trigger force. Inthis position, the support element 134 and the tab 139 engage with aportion of the needle hub 142 that prevents removal of the needle huband cannula from the retraction barrel. Specifically, the needle hub 142of one or more embodiments may include a latch portion 145 that engagesthe tab 139 to prevent removal of the needle hub. In one or morealternative embodiments, the proximal end 199 of the trigger element 199may have a narrowed cross-sectional portion (not shown) that engages theneedle hub extension 148 such that the needle hub 142 is retained withinthe hollow interior 193 and the needle cannula 150 is not exposed.

In one or more embodiments, the connection between the stopper-engagingportion 162 and the stopper 170 may be frangible. For example, theperipheral edge 173 of the stopper 170 may have a cross-sectional widththat is greater than the cross-sectional width of the inside surface 114of the fluid barrel 110 at the retaining element 116. In suchembodiments, after a proximally-directed force has been applied to theplunger rod 160 and the stopper 170 and the stopper 170 has moved to theproximal end 119 of the fluid barrel, the retaining element 116 engagesthe peripheral edge 173 of the stopper 170 and prevents the peripheraledge 173 of the stopper from moving proximally past the retainingelement 116. In such embodiments, the continued application of a forcein the proximal direction or the application of a proximally-directedforce causes the connection between the stopper-engaging portion 162 andthe stopper 170 to break. This breakage prevents a user fromdisassembling the parts of the retractable syringe assembly. Withoutbeing limited by theory, it is believed that the force required to breakthe connection between the stopper-engaging portion 162 and the stopper170 is less than the force exerted by the retaining element 116 on theperipheral edge 173 of the stopper.

In embodiments which do not incorporate a reuse prevention feature, theuser applies a force to the plunger rod 160 in the proximal direction tomove the plunger rod 160 and the stopper 170 in the proximal direction.The movement of the plunger rod 160 and the stopper 170 in the proximaldirection creates a vacuum within the fluid barrel 110. In thisposition, the trigger element 190 does not apply the trigger force tothe support element 134 and the support element 134 and the tab 139continue to apply a force on the needle hub 142 in the distal directionthat is greater than the force applied to the needle hub 142 by thebiasing element 152 in the proximal direction. After the desired amountof liquid is aspirated into the fluid barrel 110, the user applies aforce on the plunger rod 160 in the distal direction. As the plunger rod160 and the stopper 170 move in the distal direction, the triggerelement 190 also moves with the plunger rod 160 in the distal direction.Once all of the contents of the fluid barrel 110 are expelled by thestopper and the stopper 170 is in contact with the distal wall 117, thetrigger element 190 applies a trigger force on the support element 134and moves the support element 134 and the tab 139 radially outwardly sothey no longer apply a force to the needle hub 142 in the distaldirection and is released. The force applied to the needle hub 142 inthe distal direction is released because the support element 134 and thetab 139 are no longer supporting the needle hub extension 248. The forceapplied to the needle hub 142 in the proximal direction by the biasingelement 152 then drives the needle hub 142 and the needle cannula 150into the retraction barrel.

An alternative embodiment of the present invention is shown in FIGS.12-22. FIGS. 12-22 show a retractable syringe assembly 200 that includesa fluid barrel 210 and a retraction barrel 220 as otherwise describedherein. The retractable syringe also includes a needle hub assembly 240,a plunger rod 260, stopper 270 and a trigger element 290. The fluidbarrel shown in FIGS. 14-15, includes a distal end 211, a open proximalend 219, a sidewall 212 extending from the distal end 211 and theproximal end 219 including an inside surface 214 defining a chamber 215.The inside surface 214 defines a cross-sectional width and may include areuse prevention feature. The distal end 211 includes a distal wall 217that encloses the distal end 211. In the embodiment shown, the sidewall212 includes a first aperture 218 for permitting fluid communicationbetween the fluid barrel and the retraction barrel. As will be discussedin greater detail below, the first aperture 218 also permits fluidcommunication between a needle cannula disposed within the retractionbarrel 220 and the retraction barrel 220 and the fluid barrel 210.

The fluid barrel 210 shown in FIGS. 14-15 includes a reuse preventionfeature. Specifically, the fluid barrel 210 includes a retaining element216 shown in the form of a rib that extends around the entirecircumference of the inside surface 214 of the fluid barrel 210 at alocation adjacent to the proximal end 219 of the fluid barrel, asdescribed above with reference to FIG. 4.

The retraction barrel 220 is disposed adjacent to the sidewall 212 ofthe fluid barrel 210 in the embodiment shown in FIGS. 14-15. Theretraction barrel 220 is configured to house a needle hub assembly 240therein and the retraction feature. The retraction barrel 220 includesan open distal end 221 and an open proximal end 229. A wall 222 havingan interior surface 224 defining the needle chamber 225 extends from theopen distal end 221 to the open proximal end 229. The wall 222 of theretraction chamber is adjacent to the sidewall 212 of the fluid barrel210. In one or more embodiments, the wall 222 may extend around theportions of the retraction barrel 220 that are not in direct contactwith fluid barrel 210 and the sidewall 212 may form the barrier betweenthe retraction barrel 220 and the fluid barrel 210. In other words, theoutside surface of the sidewall 212 may form the interior surface 224 ofthe retraction barrel 220 along the portion of the retraction barrel 220that is in direct contact with the fluid barrel 210.

The size of the needle chamber 225 may be modified to accommodate theneedle hub assembly 240 and/or the retraction feature. According to oneor more embodiments, the interior surface 224 of the retraction barrel220 has a cross-sectional width that is smaller than the firstcross-sectional width of the fluid barrel 210. In specific embodiments,the cross-sectional width of the interior surface 224 of the retractionbarrel is less than about 90%, 80%, 70%, 60%, 50%, 40%, 30%, or 20% ofthe cross-sectional width of the inside surface 214 of the fluid barrel.Such designs in which the cross-sectional width of the interior surface224 of the retraction barrel is less than the cross-sectional width ofthe inside surface 214 of the fluid barrel, provides ergonomic andfunctional advantages. For example, the overall appearance and handlingof the dual barrel syringe is more appealing to the user.

The open distal end 221 of the retraction barrel 220 in the embodimentshown includes a barrier wall 227 that partially encloses the opendistal end 221. The open distal end 221 may be free of a barrier wall227 and may be fully open. The wall 222 may include a second aperture228 that permits fluid communication with the fluid chamber 215 and theneedle chamber 225. The second aperture 228 of the wall may also allowfluid communication between the fluid chamber 215, needle chamber 225and the needle cannula. The fluid communication between the fluid barrel210 and retraction barrel 220 may be provided by a first conduit 230that extends from a first aperture 218 of the fluid barrel 210 and thesecond aperture 228 of the retraction barrel. In the embodiment shown,the first conduit 230 extends along the width of the sidewall 212 andthe wall 222.

The needle hub assembly may include a second conduit 232 that extendsfrom an open end of the needle cannula to second aperture 228 of theretraction barrel. The second conduit 230 may include an opening 233that must be aligned with the second aperture 228 to permit fluidcommunication between the needle cannula and the fluid barrel.

The needle hub assembly 240 is disposed within the retraction barrel 220and includes a needle hub 242 and a needle cannula 250 attached to theneedle hub 242. The needle hub 242 includes a distal end 241 and aproximal end 249. The needle cannula 250 includes a free and open distalend 251 end and an open proximal end 259 that is attached to the distalend 241 of the needle hub. The needle hub 242 shown in FIG. 17 includesa needle hub body 244, a needle hub support 246 disposed distallyadjacent to the needle hub body and a needle hub extension 248 thatextends in the proximal direction from the needle hub body 244. Theneedle hub support 246 includes a recessed portion 247 for partiallyhousing the proximal end 259 of the needle cannula. In the embodimentshown, the recessed portion 247 includes a portion of the second conduit232 that extends through the needle hub 242 to the second aperture 228of the retraction barrel. In one or more alternative embodiments, theproximal end 259 of the needle cannula may extend through the recessedportion 247 to the second conduit 232, which is located fully within theneedle hub body 244 and does not extend into the needle cannula support246. The needle hub extension 248 extends into the needle chamber 225forms part of the retraction feature of the retractable syringe assembly200. The needle hub extension 248 is shown in FIG. 17 is provided in theform of an elongate rod that is cylindrical in shape. However, theneedle hub extension may have other shapes. The needle hub extension ofthe embodiments shown in FIG. 17 includes an outwardly extending latchportion 245 that engages the support element 234 of the wall, as will bedescribed in greater detail below.

The needle cannula 250 of the needle hub assembly 240 is biased to movein the proximal direction. In the embodiment shown, the needle hubassembly 240 is biased to move in the proximal direction. In theembodiment shown, the needle hub assembly 240 is biased to move in theproximal direction by a biasing element 252 disposed between the needlehub 242 and the barrier wall 227 of the retraction barrel 220. Thebiasing element 252 may include a spring 253, which may be a compressionspring that applies a constant force on the needle hub 242 in theproximal direction. In alternative embodiments, the biasing element 252may be provided in another form, for example, a lever arm (not shown)may be disposed between the needle hub and the barrier wall. Theretraction barrel 220 includes a supporting element 234 that preventsthe needle hub from moving in the proximal direction. As will beexplained in greater detail below, the release of the supporting element234 will allow the biased needle hub 242 and the needle cannula 250attached thereto to retract into the retraction barrel 220. In one ormore variants, portion of the needle hub 242 may be biased. For example,the needle cannula support 246 and the needle hub extension 248 may beprovided as separate components from the needle hub body 244 and may bebiased and so that when the support element 234 is released, the needlehub extension 248 and the needle cannula support 246 may be retractedwith the needle cannula 250 into the retraction barrel 220, while theneedle hub body 244 remains stationary.

The needle hub assembly is sized moveable within the needle chamber. Thesize and shape of the needle hub assembly may be modified to permitmovement in needle chambers having different sizes. In the assembledstate, prior to use, the needle hub assembly is positioned at the opendistal end of the retraction barrel.

The wall 222 of the retraction barrel 220 includes the supportingelement 234 that engages at least a portion of the needle hub assembly240 or interacts with the needle hub assembly 240 to provide a force inthe distal direction to the needle hub assembly 240 such that the needlehub assembly 240 is positioned at the open distal end 221 of theretraction barrel. Specifically, the needle hub assembly 240 ispositioned so the needle cannula 250 extends beyond the open distal end221 of the retraction barrel in a first position. In the first position,the supporting element 234 engages the latch portion 245 of the needlehub extension 248 and allies a force on the needle hub 242 in the distaldirection that is greater than the force applied to the needle hub 242in the proximal direction by the biasing element 252. The supportingelement 234 in the embodiment shown is provided in the form of aflexible arm 235 that is attached to the wall 222 of the retractionbarrel. The wall 222 includes an opening 236 that permits the flexiblearm 235 to flex outwardly. In the embodiment shown, the flexible arm 235includes a distal end 237 that is attached to the wall 222 and a freeproximal end 238 including a tab 239 that extends radially inwardly intothe needle chamber 225. The tab 239 specifically engages the latchportion 245 of the needle hub extension and supports the needle hubextension 248. The tab 239 and the flexible arm 235 are sized and shapedto engage the latch portion 245 of the needle hub extension and tocompress the biasing element 252 so the needle hub assembly ispositioned in the first position. To retract the needle cannula 250 intothe retraction barrel 220, as will be described in greater detail below,the flexible arm 235 is moved to release the latch portion 245 of theneedle hub assembly 240. In other words, the flexible arm 235 is movedto a position in which the tab 239 is not longer engaged with the latchportion 245 and the support element 234 no longer applies a force on theneedle hub extension 248 or needle hub 242 in the distal direction thatis greater than force applied to the needle hub 242 in the proximaldirection by the biasing element 252.

A plunger rod 260 is disposed within the fluid chamber 225. The plungerrod 260 includes a distal end 261 and a proximal end 269. The plungerrod 260 includes a stopper-engaging portion 262 extending from thedistal end 261 to a plunger rod body 263. In one or more embodiments,the plunger rod body 263 may extend from the stopper-engaging portion262 to the proximal end 269 of the plunger rod. In the embodiment shownin FIG. 16, the plunger rod body 263 extends from the stopper-engagingportion 262 to a reuse prevention feature that extends from the plungerrod body 263 to a thumb press 264 that is disposed at the proximal end269 of the plunger rod. The thumb press 264 may include a thumb presssupport 284.

The stopper-engaging portion 262 includes an annular disc 265 disposedat the distal end of the plunger rod and a narrowed portion 266extending from the annular disc 265 to the plunger rod body 263. Theannular disc 265 engages a stopper 270 so it is disposed at the distalend of the plunge rod. In one or more embodiments, the narrowed portion266 of the plunger rod 260 and the stopper 270 may be shaped to providerelative movement of the plunger rod 260 with respect to the stopper270. In one or more alternative embodiments, the plunger rod 260 may beattached to the stopper 270 in a fixed relationship.

As shown in FIG. 14, the stopper 270 has a distal end 271, a proximalend 279, a stopper body 272 and a peripheral edge 273 which forms a sealwith the inside surface 214 of the fluid barrel 210. In one or moreembodiments, the peripheral edge 283 of the stopper 270 hascross-sectional width that permits the stopper 270 to slide in theproximal and distal directions within the fluid barrel. The stopper 270may include an optional elongate tip (not shown) on its distal end 271to facilitate reduction of the residual fluid and expulsion of fluidfrom the fluid barrel.

The stopper 270 includes a stopper body 274 extending from theperipheral edge 273 to the proximal end 279. The stopper body 274includes a recess 275 that is defined by an inside surface 276. Therecess 275 includes a neck portion 277 disposed adjacent to the proximalend 279, wherein the cross-sectional width of the inside surface 276 atthe neck portion 277 is less than the cross-sectional width of theinside surface 276 at the remaining locations of the recess 275. Therecess 275 allows the stopper-engaging portion 262 of the plunger rod260 to connect to the stopper 270. The annular disc 265 engages the neckportion 277 to retain the stopper 270 on the plunger rod 260. In one ormore alternative embodiments, detents (not shown) or tabs (not shown) onthe stopper 270 and/or the stopper-engaging portion 262 may be used toretain the stopper 270 on the plunger rod 260.

The plunger rod 260 and the stopper 270 have structure to providerelative movement of the plunger rod 26 with respect to the stopper 270,as described above with reference to FIGS. 5 and 7-8. FIGS. 18-19illustrate structure to provide relative movement of the plunger rod 260and the stopper 270. Specifically, the stopper-engaging portion 262 isable to move in the proximal and distal directions within the recess 265of the stopper. When the stopper-engaging portion 262 is positionedadjacent to or in contact with the neck portion 278, the length of theplunger rod and stopper is maximized. When the stopper-engaging portion262 is disposed at a distance from the neck portion 278 the length ofthe plunger rod and the stopper is shortened.

The plunger rod 260 may also include a reuse prevention feature, forexample, a flexible protrusion 267 as described above with reference toFIGS. 5 and 7-11 that interacts with a retaining element 226 disposed onthe inside surface 224 of the fluid barrel, as described above withreference to FIGS. 4 and 7-11. The plunger rod 260 may also include afrangible portion 268 that breaks upon application of a force on theplunger rod 260 in the proximal direction after the reuse preventionfeature is activated and the plunger rod 260 is locked within the fluidbarrel 210.

In use, as shown in FIG. 20, the stopper 270 is in contact with thedistal wall 217 of the fluid barrel. In embodiments which utilize aplunger rod and stopper that permit relative movement of the plunger rodwith respect to the stopper, the plunger rod is positioned such that thestopper-engaging portion 272 is in contact or adjacent to the neckportion 278. The length of the plunger rod 260 and the stopper 270 ismaximized in this configuration. As the user applies a force on theplunger rod in the proximal direction to fill the fluid barrel, theplunger rod 260 and the stopper 270 move together in the proximaldirection. The vacuum created by this movement draws liquid into thefluid barrel 210. In embodiments which utilize a reuse preventionfeature on the plunger rod and/or fluid barrel, the reuse preventionfeature is not yet activated. In embodiments which utilize a flexibleprotrusion on the plunger rod and a retaining element on the syringebarrel, as described above with respect to FIGS. 7-11, the flexibleprotrusion 267 remains positioned proximally adjacent to the retainingelement 216.

After the desired amount of liquid is drawn into the fluid barrel 210,the user applies a force on the plunger rod 260 in the distal direction.In the embodiment shown, the trigger element 290 and the plunger rod 260are attached as a single unit and therefore, the trigger element 290moves with the plunger rod 260 in the distal direction.

When the entire contents of the fluid barrel 210 are expelled and thestopper 270 is in contact with the distal wall 217, the trigger element290 applies a trigger force on the support element 234 and causes thesupport element 234 to move radially outwardly such that the tab 239 isno longer engaged with the latch portion 245 and the force applied tothe needle hub 242 by the biasing element 152 causes the needle hub 242and the needle cannula 250 to retract into the retraction barrel. Whenthe stopper is in contact with the distal wall 217, the protrusion 267moves distally past the retaining element 216 of the fluid barrel 210and locks the plunger rod 260 into the fluid barrel 210. Application ofa force in the proximal direction on the plunger rod 260 that is greaterthan the break force required to break the frangible portion 268 of theplunger rod 260.

A third aspect of the retractable syringe assembly 300 is shown in FIGS.23-27. The retractable syringe assembly includes a single barrel 301with a dividing wall 302 that divides the barrel 301 into a fluid barrel310 and a retraction barrel 320.

In the embodiment shown in FIG. 23, the retractable syringe assemblyincludes a fluid barrel 110 and a retraction barrel 120. The retractablesyringe also includes a needle hub assembly 140, a plunger rod 160,stopper 170 and a trigger element 190.

The fluid barrel 310 may include reuse prevention feature thatcooperates with the reuse prevention feature on the plunger rod 360. Asdescribed in above with reference to FIGS. 7-11, the stopper 370 and theplunger rod 360 may have features that allow relative movement of theplunger rod 360 with respect to the stopper 370, as described above withrespect to FIGS. 7-11. In one or more alternative embodiments, theplunger rod 360 may be attached to the stopper 370 in a fixedrelationship.

The fluid barrel 310 and the retraction barrel 320 include a distal end311, a open proximal end 319, a sidewall 312 extending from the distalend 311 and the proximal end 319 including an inside surface 314defining a chamber 315. The inside surface 314 defines a cross-sectionalwidth and may include a reuse prevention feature, that will be discussedin greater detail below. The distal end 311 of the fluid barrel 310includes a distal wall 317 that encloses the distal end 311, while thedistal end 311 of the retraction barrel includes an opening 322. In theembodiment shown, the dividing wall 302 includes a first aperture 318for permitting fluid communication between the fluid barrel and theretraction barrel. As will be discussed in greater detail below, thefirst aperture 318 also permits fluid communication between a needlecannula disposed within the retraction barrel 320 and the retractionbarrel 320 and the fluid barrel 310.

The retraction barrel 320 is configured to house a needle hub assembly340 therein and the retraction feature. The retraction barrel 320includes an open distal end 321 and a closed proximal end 329. Thesidewall 312 and the dividing wall 302 form a needle chamber 325 thatextends from the open distal end 321 to the open proximal end 329. Thesize of the needle chamber 325 may be modified to accommodate the needlehub assembly 340 and/or the retraction feature. According to one or moreembodiments, the interior surface 324 of the retraction barrel 320 has across-sectional width that is smaller than the first cross-sectionalwidth of the fluid barrel 310. In specific embodiments, thecross-sectional width of the interior surface 324 of the retractionbarrel is less than about 90%, 80%, 70%, 60%, 50%, 40%, 30%, or 20% ofthe cross-sectional width of the inside surface 314 of the fluid barrel.Such designs in which the cross-sectional width of the interior surface324 of the retraction barrel is less than the cross-sectional width ofthe inside surface 314 of the fluid barrel, provides ergonomic andfunctional advantages. For example, the overall appearance and handlingof the dual barrel syringe is more appealing to the user.

The open distal end 321 of the retraction barrel 320 in the embodimentshown includes a tapered 327 that partially encloses the open distal end321. In an alternative embodiment, the open distal end 321 may be freeof a barrier wall 327 and may be fully open. The first aperture 318 ofthe wall may also allow fluid communication between the fluid chamber315, needle chamber 325 and the needle cannula. The fluid communicationbetween the fluid barrel 310 and retraction barrel 320 may be providedby a first conduit 330 that extends from a first aperture 318 of thefluid barrel 310.

The needle hub assembly may include a second conduit 332 that extendsfrom an open end of the needle cannula to second aperture 328 of theretraction barrel. The second conduit 330 may include an opening 333that must be aligned with the second aperture 328 to permit fluidcommunication between the needle cannula and the fluid barrel.

The needle hub assembly 340 is disposed within the retraction barrel 320and includes a needle hub 342 and a needle cannula 350 attached to theneedle hub 342. The needle hub 342 includes a distal end 341 and aproximal end 349. The needle cannula 350 includes a free and open distalend 351 end and an open proximal end 359 that is attached to the distalend 341 of the needle hub. The needle hub 342 shown in FIG. 23-27 may bethe same as described above with reference to FIG. 17.

The needle cannula 350 of the needle hub assembly 340 is biased to movein the proximal direction. In the embodiment shown, the needle hubassembly 340 is biased to move in the proximal direction. In theembodiment shown, the needle hub assembly 340 is biased to move in theproximal direction by a biasing element 352 disposed between the needlehub 342 and the barrier wall 327 of the retraction barrel 320. Thebiasing element 352 as otherwise described herein that applies aconstant force on the needle hub 342 in the proximal direction. Inalternative embodiments, the biasing element 352 may be provided inanother form, for example, a lever arm (not shown) may be disposedbetween the needle hub and the barrier wall. The retraction barrel 320includes a supporting element 334 that prevents the needle hub frommoving in the proximal direction. As will be explained in greater detailbelow, the release of the supporting element 334 will allow the biasedneedle hub 342 and the needle cannula 350 attached thereto to retractinto the retraction barrel 320. In one or more variants, portion of theneedle hub 342 may be biased.

The needle hub assembly is sized moveable within the needle chamber. Thesize and shape of the needle hub assembly may be modified to permitmovement in needle chambers having different sizes. In the assembledstate, prior to use, the needle hub assembly is positioned at the opendistal end of the retraction barrel.

In the embodiment shown in FIGS. 23-27, the retraction mechanism is notdriven by a separate trigger element but rather, by the internalstructure of the plunger rod 360 and the syringe barrel 301.Specifically, the dividing wall 302 includes a supporting element 303that engages at least a portion of the needle hub assembly 340 orinteracts with the needle hub assembly 340 to provide a force in thedistal direction to the needle hub assembly 340 such that the needle hubassembly 340 is positioned at the open distal end 321 of the retractionbarrel. Specifically, the needle hub assembly 340 is positioned so theneedle cannula 350 extends beyond the open distal end 321 of theretraction barrel in a first position. In the first position, thesupporting element 334 provides a force on the needle hub 342 in thedistal direction that is greater than the force applied to the needlehub 342 in the proximal direction by the biasing element 352. Thesupporting element 334 in the embodiment shown in FIG. 23A is providedin the form of a perpendicular tab 304 that is disposed on the dividingwall 302 and extends into the needle chamber 325 and a ramped portion307 that is disposed on the dividing wall 302 and extends into the fluidchamber 315. As shown in FIG. 25A, the dividing wall 302 includes anopening 305 that permits the perpendicular tab 304 to flex outwardlyinto the fluid chamber 325 as the plunger rod interacts with the rampedportion 307. In the embodiment shown, the portion of the dividing wall302 adjacent to the perpendicular tab 304 also flexes inwardly to movethe perpendicular tab 304. The perpendicular tab 304 is sized and shapedto support the needle hub 342 and the needle cannula 350 and to compressthe biasing element 352 so the needle hub assembly is positioned in thefirst position. To retract the needle cannula 350 into the retractionbarrel 320, as will be described in greater detail below, theperpendicular tab 304 is moved to release the needle hub assembly 340.In other words, the perpendicular tab 304 is moved to a position inwhich it can no longer support the needle hub 342 and apply a force onthe needle hub 342 in the distal direction that is greater than forceapplied to the needle hub 342 in the proximal direction by the biasingelement 352.

The retraction mechanisms utilized in the retractable syringe assemblies100, 200 and 300 described herein may be substituted with the retractionmechanisms described in provisional application P-9275 (U.S. ProvisionalPatent No. 61/366,874). Specifically, the retraction mechanisms shown inFIGS. 8-12, 24-29 and 33-37.

A plunger rod 360 is disposed within the fluid chamber 325. The plungerrod 360 includes a distal end 361 and a proximal end 369. The plungerrod 360 includes a stopper-engaging portion 362 extending from thedistal end 361 to a plunger rod body 363, which may be shaped and sizedas described otherwise herein with respect to retractable syringeassemblies 100 and 200. In one or more embodiments, the plunger rod body363 may extend from the stopper-engaging portion 362 to the proximal end369 of the plunger rod. In the embodiment shown in FIGS. 23-27, theplunger rod body 363 extends from the stopper-engaging portion 362 to areuse prevention feature that extends from the plunger rod body 363 to athumb press 364 that is disposed at the proximal end 369 of the plungerrod. The thumb press 364 may include a thumb press support 384.

The plunger rod body 363 includes a projection 306 that extends radiallyoutwardly from the plunger rod body 363. The projection 306 is shaped,sized and positioned to interact with the ramped portion 307 of thedividing wall 302. Specifically, the projection 306 applies a distallydirected force on the ramped portion 307 to cause the dividing wall 302and the perpendicular tab 304 to flex or move into the fluid chamber,thereby releasing the force applied to the needle hub 342 in the distaldirection and allowing the force applied to the needle hub 342 by thebiased element 352 to retract the needle hub and needle cannula into theretraction barrel. The stopper 370 is attached to the stopper engagingportion 362 and may be shaped and sized as described otherwise withreference to retractable syringe assemblies 100 and 200. The stopper 370may be shaped and sized and include features to permit the plunger rodto move in the proximal and distal directions relative to the stopper.

As shown in FIGS. 24-25, after the desired amount of fluid is aspiratedinto the fluid barrel, a force is applied to the plunger rod 360 in thedistal direction to expel the contents of the fluid barrel. As theplunger rod 360 moves in the proximal direction and the projection 306applies a force on the ramped portion 307 in the distal direction thatcauses the dividing wall 302 and the perpendicular tab 304 to flexinwardly and release the needle hub so that the biasing element causesthe needle hub to retract into the retraction barrel, as shown in FIG.26. The reuse prevention features of the retractable syringe barrel alsolock the plunger rod 360 into the fluid barrel 310 as otherwisedescribed herein and as shown in FIG. 27.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe invention. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the invention.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present invention without departing from the spirit andscope of the invention. Thus, it is intended that the present inventioninclude modifications and variations that are within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A syringe assembly comprising: a fluid barrelincluding an open proximal end, a distal end including a distal wall, asidewall extending from the distal end and the proximal end including aninside surface defining a chamber; a retraction barrel disposed adjacentto the sidewall of the fluid barrel, the retraction barrel including awall having an interior surface defining a needle chamber, an openproximal end, an open distal end including a barrier wall, an aperturebetween the wall of the fluid barrel and the sidewall of the fluidbarrel such that the fluid chamber and the needle chamber are in fluidcommunication; a plunger rod disposed within the fluid chambercomprising a thumb press, a distal end, a proximal end, astopper-engaging portion extending from the distal end to a plunger rodbody; the plunger rod body extending from the distal end to the proximalend, a flexible protrusion disposed proximally adjacent to the plungerrod body, and a frangible portion disposed between the flexibleprotrusion and the thumb press; a stopper disposed on thestopper-engaging portion; a needle hub assembly comprising a needle hub,a needle cannula attached to the needle hub in fluid communication withthe aperture, the needle hub assembly biased to move in the proximaldirection; and a trigger element moveable with the plunger rod andextending into the needle chamber of the retraction barrel, the triggerelement providing a trigger force causing the needle cannula to retractinto the retraction barrel.
 2. The syringe assembly of claim 1, whereinthe frangible portion includes a support member that extends from theflexible protrusion to a plurality of point connections that connect thesupport member to the thumb press.
 3. The syringe assembly of claim 2,wherein the support member has a cross-sectional width that increasesfrom a distal end of the support member adjacent to the flexibleprotrusion to a proximal end of the support member.
 4. The syringeassembly of claim 2, wherein the support member had a circularcross-section
 5. The syringe assembly of claim 2, wherein the pluralityof point connections are disposed at a peripheral edge of the proximalend of the support member.
 6. The syringe assembly of claim 2, whereinthe point connections are discrete connections that form a narrowedconnection point between the support member and the thumb press.
 7. Thesyringe assembly of claim 1, wherein the fluid barrel includes aretaining element.
 8. The syringe assembly of claim 7, wherein theretaining element is a ring that extends around the inside surface ofthe fluid barrel.
 9. The syringe assembly of claim 8, wherein theretaining element is disposed adjacent to the proximal end of the fluidbarrel.
 10. The syringe assembly of claim 1, wherein the needle hubassembly is disposed within the retraction barrel.
 11. The syringeassembly of claim 1, wherein the needle hub includes a needle hub body,a needle hub support disposed distally adjacent to the needle hub bodyand a needle hub extension that extends in the proximal direction fromthe needle hub body.
 12. The syringe assembly of claim 11, wherein theneedle hub extension includes a latch portion that extends radiallyoutwardly from the needle hub extension.
 13. The syringe assembly ofclaim 11, wherein the needle hub support includes a recessed portion forpartially housing the proximal end of the needle cannula.